


The Improbable Existence of Fireflies

by TheThirdTemptationOfParis



Category: Sherlock (TV)
Genre: Angst and Hurt/Comfort, M/M, Miscommunication, Mutual Pining, Mycroft Being a Good Brother, No Character Death, Rosie has cancer, Rosie is too smart for her own good, Sickfic, Slow Burn, Title will make sense later, also he has a soft spot for Rosie, tags may get added
Language: English
Status: In-Progress
Published: 2018-03-23
Updated: 2018-03-23
Packaged: 2019-04-07 02:19:43
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,385
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14070729
Author URL: https://archiveofourown.org/users/TheThirdTemptationOfParis/pseuds/TheThirdTemptationOfParis
Summary: Rosamund Scott Watson, as she was now known, was diagnosed with acute myeloid leukemia when she was four years old.The story of how two men work together to raise a little girl and find their way to each other.





	The Improbable Existence of Fireflies

Rosamund Scott Watson, as she was now known, was diagnosed with acute myeloid leukemia when she was four years old. Everything that had happened in John’s life leading up to that moment was nothing compared to the heart-stopping diagnosis. His father’s abuse, his mother’s death, the war, James, Sherlock, Mary, all of it couldn’t compare to the packet of paper in his hands. Sherlock sat beside him, Rosie on his lap, head lowered, silent tears falling into the girl’s curly mop. 

“I don’t…” John stammered, “I don’t understand.” He didn’t mean he didn’t understand the diagnosis. He was a doctor, of course he understood it. His daughter’s bone marrow wasn’t doing what it was supposed to and if they hadn’t caught it… no. What he didn’t understand was how his daughter, his Rosie, could have possibly become a part of this extremely small statistic.

“John,” the doctor, Mitali de la Croix, a kind woman with an even kinder face, said, trying to placate him, “it’s very fortunate that we caught this as soon as we did. Any later and it could have been more malignant than it already is.”

Sherlock’s inhales were audible now, which sent Rosie into her ‘Sherlock’s Protector’ mode, “Sherlock,” she whispered, turning to face him, a small hand imitating tucking his curls behind his ear like he did for her when she cried, “why sad?” The concern in her small voice broke John’s heart.

“It’s nothing, _mon petit bijou_. I’m alright,” he whispered, kissing her forehead. When he pulled back, John saw the watery, fake smile on his lips and the burning question in his mind, _How the hell do you tell a four year old she has cancer?_

“There’s a proposed chemotherapy regimen and payment plan in the packet. If there’s anything else I can do at this stage, please don’t hesitate to give me a call.” She rose and extended a hand to John, which he shook, and to Sherlock, who begrudgingly did the same.

The three of them walked out, Rosie with one arm wrapped Sherlock’s neck, and the other reaching down to grip John’s little finger, not understanding why they both looked so sad.

***

They left Rosie with Mrs. Hudson when they returned to Baker Street, knowing they needed to discuss what comes next. After climbing the seventeen steps to 221B and hanging their coats, Sherlock said, “I’m calling Mycroft.”

John whirled on him, “No the hell you’re not. She’s my daughter, Sherlock.”

“Exactly, and I vowed to protect her, John. From everything.”

“We agreed, Sherlock. We agreed when we took her for her tests that we wouldn’t get him involved.” 

“We agreed we wouldn’t get him involved _unless it was serious_. A diagnosis seems pretty damn serious to me.”

John scoffed, “You and you’re fucking loopholes. How many times have I told you to quit doing that?”

“John, please don’t be obtuse.” Sherlock was pleading. It seemed to John that he would fall to his knees and fully beg before long.

“She’s not your daughter, Sherlock! You don’t get to make this decision!” John felt his temper rising.

“You’re right, she’s not, but I vowed to protect her. Albeit this isn’t the threat I thought would come, but nevertheless.” His chest was rising and falling in quick succession, “Before she was born, when she was born, after everything, I swore I would always put her first. Always. Mycroft will give us the best chance. The best doctors, the best treatment, whatever the cost. Please, John. Let me call Mycroft.”

John looked at the man before him, the man who had tried his hardest to prove himself to John in the last few years, even stepped back from whatever it was they were about to cross, all for him and Rosie. The least he could do in that moment was let him call his brother for help. John nodded.

Sherlock dialed the number and pressed the phone to his ear. Mycroft, out of his ordinary fashion, seemed to pick up on the first ring, voice so frantic John could hear it through the speaker, “What’s happened, brother dear?” 

“Rosie’s tests…” Sherlock choked, tears gathering in his eyes again. John had never seen his heart so clearly, “Rosie’s tests came back positive… for acute myeloid leukemia. Mycroft, she…” 

“I’m on my way.” The click of the receiver, the finality of Mycroft’s tone, all of it spoke volumes to John. The Holmes brothers would do absolutely anything for the Watsons. Anything. John would never take anything either of them did for granted again. 

Mycroft arrived ten minutes later, and, just as she always did, Rosie knew when Uncle Myc was in the building. The tapping of his umbrella gave him away every time. From upstairs John could hear her squeal of delight, “Uncle Myc, Uncle Myc, Uncle Myc!” The patter of toddler feet leaving Mrs. Hudson’s flat.

“ _Princesse Rosamund_.” There was a groan as he hoisted her into the air, “Let’s go see what Daddy and Sherlock are up to, hm?” When the two entered the flat, the umbrella was forgotten in the entryway in favor of much more precious cargo.

Mycroft scanned Sherlock and John for a moment, “You haven’t explained it to her yet, have you?”

John shook his head.

“We were too busy worrying about what to do with the information ourselves before we tried explaining it,” Sherlock said, looking a bit ashamed.

Mycroft sat carefully on the couch, settling Rosie in his lap, “ _Abeille_ ,” he said softly, “do you know how you’ve been getting really sick lately?”

Rosie nodded, “I’m not allowed to go to school and play with Nessa and Lea because Daddy said it could get me really sicker.”

“And Daddy’s right,” Mycroft said, “that’s why he took you to the doctors so they could figure out how to make it so you wouldn’t get sick anymore.”

Rosie pulled her grumpy face, “The doctors poked me and made my arm ouch.”

“Can I tell you something important, _abeille_?”

“A secret?”

Mycroft laughed, “Not quite. Uncle Myc is going to do everything he can to make sure you’re not sick anymore, but you’re going to have to be a big girl. Can you do that, Rosamund?” Rosie nodded, smiling, then putting on her brave face like she did for John and Sherlock the day of her tests. Mycroft smiled back, “That’s my girl. How about I take you back down to Nana Hudson so I can talk to Daddy and Sherlock? I think she was about to bake some biscuits and could use some help.”

Rosie nodded and let herself be carried back downstairs, one of the worst parts of the process now behind them. Mycroft returned moments later, face solemn, “I wasn’t lying to her. I will do everything possible to fix it.”

Sherlock nodded, collapsing in his chair. John could see his throat working, trying to form words, “I didn’t know what else to do.”

John sat in his own chair, still a bit disdainful about having to ask for help and he knew Mycroft could see it, “Doctor Watson,” he remarked, “I know you’re a proud man, but I swear to you that this is not something that I take lightly.”

“I understand, Mycroft, I do, but…”

Sherlock interrupted him, “John, just for once in your life, swallow your pride and let someone help you. It’s not a sin to ask for help.”

“I know it’s not, but I feel hopeless. I couldn’t explain to my own daughter why the doctors had to keep sticking her with needles! Bloody Mycroft had to obliquely explain cancer!”

Mycroft cleared his throat, “I know things are and have been difficult, but I see you and Rosamund as family and it is within my power to help. One thing I will not do is stand aside as I watch you all struggle. Contrary to popular belief, I’m not as heartless as I once was.”

John looked from Mycroft to Sherlock, who held his gaze, “Let him help, John. Please. For Rosie.”

John dropped his head into his hands and cried for the first time since this process began. He cried for himself, for Rosie, for Sherlock because he knew that he was suffering just as much as he was, “Whatever you need to do, Mycroft. Please. And thank you.”

Mycroft placed a steady hand on John’s shoulder and walked out of the flat to call people. John and Sherlock sat and just looked at each other, not saying anything. John’s throat worked around the words he held there, all the thank yous and apologies he should have said years ago but kept at bay because it would lead to something… more. Something that he didn’t think either of them were ready for, even after almost eleven years. 

Before either of them could dare to say something heartfelt, Mycroft returned with Rosie wrapped around his little finger and a plate of biscuits in his hand, “Miss Rosamund requested that I bring these to the two of you.”

Rosie smiled and launched to John, climbing into his lap cuddling into his side. John smiled somewhat sadly and kissed her forehead, “Thank you, love. Are you and Nana Hudson done?”

She shook her head, “We’re gonna make cake! Chocolate peanut butter!”

John gasped, “Your favorite! You better get back down there or she’s gonna start without you.” 

Rosie smiled up at him and climbed out of his lap, waddling across the floor to climb into Sherlock’s lap and kiss his cheek. Sherlock beamed at her, “ _Merci, mon petit loup_ ,”

“Welcome!” She climbed down again and went back downstairs to 221A.

John picked up one of the biscuits and just looked at it, “Is this what the rest of her life is going to be like? Baking with Mrs. Hudson while the three of us have secret meetings in the living room?” He replaced the biscuit and sat back in his chair, thumping his head against it.

Sherlock cleared his throat, “Not always. When she gets older, she’ll understand. She’ll be able to sit in with us, have a say in what happens next.”

John swallowed as tears lined his vision again, “What if she doesn’t get older, Sherlock? What then?” 

“You can’t think like that, John. It isn’t beneficial. You know that.”

“I have to look at every possible outcome. _That_ is a feasible outcome.”

“Not if I have any say in it,” Mycroft said, voice steady, “My contacts have assured me that the best care can be put in place for Rosamund.”

John looked up at him, “Sometimes even the best care isn’t enough, Mycroft. You’re not a god. You can’t _assure_ me that whatever care you have in place will, in fact, save my daughter’s life.”

The men in the room were silent, the weight of the situation closing in around them. There were no certainties in this situation. There never were. The only thing they knew in that moment was that the little girl they all adored needed them more than anything. Now was not the time for arguments.

“Have faith, John,” Mycroft whispered, “That’s all I ask. I’m not going to ask you to believe in a cure, but just… trust the treatment.”

“I don’t trust anything right now, Mycroft. All I know to be true right now is the fact that my four year old daughter shouldn’t have fucking cancer!”

Sherlock leaned across the space between their chairs and placed a hand on his knee, “John, I know your mind is running a million miles a minute, but please, stay calm.”

John stood up, pushing Sherlock’s hand away, “Stay calm? That’s rich coming from the person who was scared to take that final step years ago. You were afraid of nothing when I met you, Sherlock, and then you _literally_ became afraid of _nothing_.”

“John, you’re not making any sense.”

“Nothing makes any sense, Sherlock! That’s a fact of our lives at this point! _Nothing ever makes sense_!” John was fuming and he could tell that it was offsetting the progress the three of them were making.

Sherlock stood and walked over to John, turning him around, “John, look at me. Please.” John did, “I know there’s turmoil in you brain right now, as there is in mine, but we need to keep ourselves composed. For Rosie’s sake.”

“How can you compartmentalize this so quick? I understand you have the intellect, but this is my daughter. I can’t do it.”

Sherlock froze for a moment and looked over his shoulder at his brother, “Mycroft, could you leave us? I think John and I have a lot more to talk about.” Mycroft nodded and let himself out. Sherlock took John by the arm and moved him back to the chairs, kneeling in front of him in some sort of supplication, “I haven’t compartmentalized anything, John. I can’t wrap my head around it either.”

John looked up, catching Sherlock’s eyes, “You’re just so rational and calm. I don’t understand.”

“You may wanna record this for the future, but I trust my brother, and I trust science. I also trust Rosamund Scott Watson will make use of her Watson gene and be strong. She’s Rosie. She’s _your_ daughter, John. She can make it through anything.”

“I think you give my Watson gene more credit than it really deserves. I’ve wanted to give up more times than I think you really understand.”

Sherlock’s fist clenched on his trouser leg, nails lightly scraping the fabric, “I understand.” He paused, jaw working as mouth tried to form words, “I’m still so sorry for everything, John.”

John ran a hand through his hair and sighed, “I told you you didn’t need to apologize anymore years ago. And I forgave you years before that.” He took another deep breath before continuing, “I know why you’re saying this but, Sherlock, we have bigger things to focus on right now. Maybe someday.”

Sherlock sat back on his heels and gazed at the floor, slightly crestfallen. He shook his head and stood up, studiously not looking at John, “I’m going to see if Rosie and Hudders need any help.” He left the flat before John could respond. The only thing ringing in John’s ears as he left was his denial of _‘Maybe someday.’ Idiot._


End file.
